Method and terminal for applying an extended access barring

ABSTRACT

Disclosed is a method for applying an extended access barring (EAB), the method performed by a machine type communication (MTC) device and comprising: recognizing, by an upper layer of the MTC device, a change from being operated in an override low priority to being operated in a low priority; informing, by the upper layer, a lower layer that the priority has been changed; and determining, by the lower layer, whether to apply the EAB, to handle at least one of an attach request, a tracking area update request, and a service request. If the EAB is applied, a RRC connection is barred.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. Provisionalapplication No. 61/676,280 filed on Jul. 26, 2012, and No. 61/679,780filed on Aug. 6, 2012, all of which are incorporated by reference intheir entirety herein.

TECHNICAL FIELD

The present invention relates to a method and terminal for applying anextended access barring (EAB).

BACKGROUND ART

In order to meet a variety of forums and new technologies related to the4th generation mobile communications, the 3rd Generation PartnershipProject (3GPP) which aims to provide technical specifications of the 3rdgeneration mobile communications system has proceeded with research forthe Long Term Evolution/System Architecture Evolution (LTE/SAE)technologies since year-end 2004 as a part of efforts to optimize andenhance performances of the 3GPP technologies.

The SAE mainly led by the 3GPP SA WG2 relates to research of networktechnologies which aims to determine a network structure together withthe LTE work of the 3GPP TSG RAN and to support mobility betweennetworks of different versions. Recently, the SAE has been consideredone of the essential standardization issues of the 3GPP. Such work is todevelop the 3GPP to be a system based on the IP and supporting a varietyof radio (wireless) connection technologies, and has progressed with theaim of an optimized packet-based system capable of minimizing atransmission delay with enhanced data transmission capability.

The SAE upper level reference model defined by the 3GPP SA WG2 mayinclude a non-roaming case and roaming cases with a variety ofscenarios. Detailed descriptions thereof are given in 3GPP TS 23.400aand TS 23.400b. FIG. 1 is a schematic reconfiguration diagram of suchnetwork structure.

FIG. 1 is view of an evolved mobile communication network.

One of the distinctive characteristics of the network structure shown inFIG. 1 is that it is based on a 2 tier model having an eNode B of theEvolved UTRAN and a gateway of the core network. The eNode B 20 has asimilar function, although not exactly the same, to the eNode B and RNCof the existing UMTS system, and the gateway has a function similar tothe SGSN/GGSN of the existing system.

Another distinctive characteristic is that different interfaces areexchanged by the control plane and the user plane between the accesssystem and the core network. While an lu interface exists between theRNC and SGSN in the existing UMTS system, two separate interfaces, i.e.,S1-MME and S1-U, are used in the Evolved Packet Core (SAE) system sincethe Mobility Management Entity (MME) 51 which handles the processing ofa control signal is structured to be separated from the gateway (GW).

For the GW, there are two types of gateways: a Serving Gateway(hereinafter, ‘S-GW’) 52 and a Packet Data Network gateway (hereinafter,‘PDN-GW’ or ‘P-GW’) 53.

FIG. 2 shows the structure and communication process of an MTC device.

A Machine Type Communication (MTC) device may be used in a mobilecommunication system. The MTC refers to data communications betweenmachines performed without human interference, and a device used forthese communications is referred to as an MTC device. A service providedby the MTC device is different from a communication service performedwith human interference, and may be applied to a variety of services.

The aforementioned MTC device is a communication device is acommunication device that performs communication between machines, whichis not much different from a UE that needs human interaction, exceptthat it needs no human interaction. That is, the MTC device maycorrespond to a UE that needs no human interaction. However, from theviewpoint that no human interaction is needed, if a messagetransmission/reception method (e.g., paging messagetransmission/reception method) for a UE that needs human interaction isfully applied to the MTC device, some problems may occur.

Referring to FIG. 2, when a measuring service, a road informationservice, a user electronic equipment calibration service, or the like,provided by the MTC device, received by an eNB, the eNB may transmit itto an MTC server, and therefore the MTC user may use the service.

It is often the case that the MTC device performs communication alone ina place that needs no human interference since it performs communicationwithout human interaction.

FIG. 3 shows an exemplary structure of a radio interface protocol in acontrol plane between the UE and the base station, and FIG. 4 shows anexemplary structure of a radio interface protocol in a user planebetween the UE and the base station.

The radio interface protocols are based on the 3GPP radio access networkstandards. The radio interface protocol has horizontal layers comprisinga physical layer, a data link layer, and a network layer, and hasvertical planes comprising a user plane (U-plane) for transmitting datainformation and a control plane (C-plane) for transmitting controlsignals (signaling).

The protocol layers can be categorized as a first layer (L1), a secondlayer (L2), and a third layer (L3) based on three lower layers of anopen system interconnection (OSI) standard model widely known in thecommunication system.

The layers of the radio protocol control plane of FIG. 3 and those ofthe radio protocol user plane will be described as follows.

The physical layer, the first layer, provides an information transferservice by using a physical channel. The physical layer and an upperlayer called a medium access control (MAC) layer are connected via atransport channel. Data is transferred between the MAC layer and thephysical layer via the transport channel. Between different physicallayers, namely, between a physical layer of a transmitting side and thatof a receiving side, data is transferred via the physical channel.

The physical channel is composed of a number of subframes present in atime axis and a number of subcarriers present in a frequency axis. Here,a single subframe includes a plurality of symbols and a plurality ofsubcarriers in the time axis. A single subframe includes a plurality ofresource blocks, and a single resource bock includes a plurality ofsymbols and a plurality of subcarriers. A single resource block iscalled a slot and has a length of 0.5 ms temporally. A TTI (TransmissionTime Interval), a unit time during which data is transmitted, is 1 mswhich corresponds to a single subframe.

Physical channels existing in the physical layers of a transmitter and areceiver include an SCH (Synchronization Channel), a PCCPCH (PrimaryCommon Control Physical Channel), an SCCPCH (Secondary Common ControlPhysical Channel), a DPCH (Dedicated Physical Channel), a PICH (PagingIndicator Channel), a PRACH (Physical Random Access Channel), a PDCCH(Physical Downlink Control Channel), and a PDSCH (Physical DownlinkShared Channel).

The MAC layer, the second layer, is connected with the physical layerthrough a transport layer, and connected to an upper layer called aradio link control (RLC) layer via a logical channel.

A downlink transport channel for transmitting data from the network tothe UE includes a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message,and a downlink shared channel (DL-SCH) for transmitting user traffic ora control message. The downlink multicast, traffic of a broadcastservice, or a control message may be transmitted via the downlink SCH ora separate downlink MCH (Multicast Channel). An uplink transport channelfor transmitting data from the UE to the network includes a randomaccess channel (RACH) for transmitting an initial control message and anuplink SCH for transmitting other user traffic or a control message.

The logical channel is divided into a control channel that transmitsinformation of the control plane and a traffic channel that transmitsinformation of the user plane according to a type of transmittedinformation.

The logical channels, which are at an upper position than the transportchannel and mapped to the transport channel, include a BCCH (BroadcastChannel), a PCCH (Paging Control Channel), a CCCH (Common ControlChannel), an MCCH (Multicast Control Channel), an MTCH (MulticastTraffic Channel), a DCCH (Dedicated Control Channel), and the like.

An RLC (Radio Resource Control) layer, the second layer, supportsreliable data transmission, guarantees quality of service (QoS) of eachradio bearer (RB), and is responsible for (or handles) datatransmission. In order to guarantee RB-specific QoS, the RLC has one ortwo independent RLC entities for each RB, and in order to supportvarious types of QoS, the RLC layer provides three RLC modes: a TM(Transparent Mode); a UM (Unacknowledged Mode); and an AM (AcknowledgedMode).

A packet data convergence protocol (PDCP) layer, the second layer,performs a function called header compression that reduces the size of aheader of an IP packet, which is relatively large and includesunnecessary control information, in order to effectively transmit the IPpacket such as an IPv4 or IPv6 in a radio interface having a smallerbandwidth. Also, the PDCP layer is used to cipher data of the C-plane,e.g., an RRC message. The PCP layer also ciphers data of the U-plane.

A radio resource control (RRC) layer located at the uppermost portion ofthe third layer is defined only in the control plane, and controls alogical channel, a transport channel, and a physical channel in relationto configuration, reconfiguration, and the release or cancellation ofradio bearers (RBs). In this case, the RBs refer to a service providedby the second layers of the radio protocol for data transmission betweenthe UE and the E-UTRAN.

When there is an RRC connection between the RRC of the UE and the RRClayer of the wireless network, the UE is in an RRC-connected mode, orotherwise, the UE is in an idle mode.

A non-access stratum (NAS) layer positioned at an upper portion of theRRC layer performs functions such as session management, mobilitymanagement, and the like.

The NAS layer illustrated in FIG. 3 will be described in detail.

An eSM (evolved session management) that belongs to the NAS layerperforms a function such as a default bearer management, a dedicatedbearer management, or the like, and is responsible for (or handles)controlling to allow the UE to use a PS service in a network. Defaultbearer resource has characteristics in that it is allocated from anetwork when the UE first accesses a particular packet data network(PDN). In this case, the network allocates an IP address that may beused by the UE to allow the UE to use a data service, and also allocatesQoS of a default bearer. In LTE, two types of bearers, i.e., a bearerhaving guaranteed bit rate (GBR) QoS characteristics that guarantee aparticular band width for a data transmission and reception and anon-GBR bearer having best effort QoS characteristics withoutguaranteeing a bandwidth, are supported. In the case of the defaultbearer, the non-GBR bearer is allocated. In the case of a dedicatedbearer, a bearer having the QoS characteristics of the non-GBR isallocated.

The bearer allocated to the UE by the network is called an evolvedpacket service (EPS) bearer, and when the network allocates the EPSbearer, the network allocates an ID. This is called an EPS bearer ID. Asingle EPS bearer has QoS characteristics of a maximum bit rate (MBR)or/and guaranteed bit rate (GBR).

FIG. 5 is a conceptual diagram showing a 3GPP service model forsupporting MTC.

Although GSM/UMTS/EPS with the 3GPP standards for supporting MTC aredefined to perform communication over a PS network, the presentspecification describes a method applicable to a CS network as well.

In the current technical specification, the use of an existing 3GPPbearer is suggested for the definition of the network structure. Amethod using a short message service (SMS) for data exchange between anMTC device and an MTC server was proposed as one of alternativesolutions. The use of SMS was proposed, considering that a small amountof digital data including meter reading information and productinformation will be an object of an MTC application in view of thecharacteristics of the MTC application, by which an existing SMS methodand an IMS-based SMS method can be supported.

In the current 3GPP standards, three architecture models for MTC aredefined as follows: a Direct Model, an Indirect Model, a Hybrid Model,and so on. The Direct Model is a model in which an MTC application isconnected directly to an UE over a 3GPP network and performscommunication under the control of a 3GPP network provider. The IndirectModel includes two models: a model in which an MTC application isconnected to an MTC server outside a 3GPP network to performcommunication with a UE under the control of an MTC service provider;and a model in which an MTC server exists within a 3GPP network and anMTC application is connected to an UE to perform communication under thecontrol of a 3GPP network provider. The Hybrid Model involves theco-existence of the Direct Model and Indirect Model. For example, userplane is a method of communication using the Direct Model and controlplane is a method of communication using the Indirect Model.

As described above, Machine Type Communication (MTC) involvescommunication performed between machines, which may result in overloadin some cases. For example, overload may be generated due to thefollowing reasons:

there is a malfunctioning in the MTC server or MTC application;

an external event triggers MTC devices to attach/connect; and

a large number of MTC devices are configured such that a specificprogram is repeatedly operated at a specific time.

FIG. 6 shows a network overload state.

As illustrated in FIG. 6, if traffic is overloaded or congested at aninterface between the (e)NodeB 20 and the S-GW 52, then downlink data tothe MTC device 10 or upload data from the MTC device 10 is failed to beproperly transmitted.

Also, if an interface between the S-GW 52 and the PDN-GW 53 or aninterface between the PDN-GW 53 and an Internet Protocol (IP) servicenetwork of the mobile communication operator is overloaded or congested,then downlink data to the MTC device 10 or upload data from the MTCdevice 10 is failed to be properly transmitted.

Also, when the MTC device is handed over from a cell being currentlyserviced to another cell, if the another cell is overloaded, then itwill cause a problem of dropping the service of the MTC device.

In order to solve the foregoing problem, mobile communication operatorshave updated the S-GW 52 and the PDN-GW 53 having high-capacity, but ithas a disadvantage of requiring very high cost. Furthermore, it has adisadvantage that the amount of transmitted or received data increasesexponentially over time, and then overloaded in a short time.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to provide a solutionto the above-described problems.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a method for applying an extended access barring(EAB), the method performed by a machine type communication (MTC) deviceand comprising: recognizing, by an upper layer of the MTC device, achange from being operated in an override low priority to being operatedin a low priority; informing, by the upper layer, a lower layer that thepriority has been changed; and determining, by the lower layer, whetherto apply the EAB, to handle at least one of an attach request, atracking area update request, and a service request. If the EAB isapplied, a RRC connection is barred.

The method may further include receiving a non-access stratum (NAS)configuration Management Object (MO) including the EAB information; andreceiving system information including EAB parameters, wherein thesystem information is broadcasted within a cell. Accordingly, in thedetermination, the NAS configuration MO and the EAB parameters may beconsidered.

The EAB parameter may include at least one of: a bitmap parameterindicating classes for which access is barred; a category parameterindicating a category of devices for which the EAB applies; and a listof Public Land Mobile Network (PLMN).

The method may further include: notifying a NAS layer of a network nodethat the priority has been changed; and receiving an instruction toapply the EAB from the NAS layer of the network node.

The upper layer may correspond to a NAS layer and the lower layer maycorrespond to a RRC layer.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is also provided a method for applying an extended access barring(EAB), the method performed by a machine type communication (MTC) deviceand comprising: receiving a non-access stratum (NAS) configurationManagement Object (MO) including the EAB information; configuring theEAB based on the received EAB information; if the EAB is configured,indicating a lower layer that the EAB applies for at least one of anattach request, a tracking area update request, and a service request,except for a case where the MTC device is configured to allow overridingEAB and receives an indication from the upper layers to override EAB.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is also provided a machine type communication (MTC) device forapplying an extended access barring (EAB), the MTC device comprising: aradio frequency (RF) unit configured to receive a non-access stratum(NAS) configuration Management Object (MO) including the EABinformation; a processor for controlling the RF unit. The processor mayconfigure the EAB based on the received EAB information; and if the EABis configured, indicate a lower layer that the EAB applies for at leastone of an attach request, a tracking area update request, and a servicerequest, except for a case where the MTC device is configured to allowoverriding EAB and receives an indication from the upper layers tooverride EAB.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is view of an evolved mobile communication network;

FIG. 2 shows the structure and communication process of an MTC device;

FIG. 3 shows an exemplary structure of a radio interface protocol in acontrol plane between the UE and the base station;

FIG. 4 shows an exemplary structure of a radio interface protocol in auser plane between the UE and the base station;

FIG. 5 is a conceptual diagram showing a 3GPP service model forsupporting MTC;

FIG. 6 shows a network overload state;

FIG. 7 shows a procedure of rejecting access from a MTC device in caseof network congestion or overload;

FIG. 8 is an exemplary view illustrating a protocol of the messageillustrated in FIG. 7;

FIG. 9 shows a procedure of barring a RRC connection in case of networkcongestion or overload;

FIG. 10 shows one example method according to a first embodiment;

FIG. 11 shows one example method according to a second embodiment;

FIG. 12 shows one example method according to a third embodiment; and

FIG. 13 is a block diagram of the MTC device and MME according to thepresent invention.

MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. It will also be apparent to those skilled in the art thatvarious modifications and variations can be made in the presentinvention without departing from the spirit or scope of the invention.Thus, it is intended that the present invention cover modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

Description will now be given in detail of a drain device and arefrigerator having the same according to an embodiment, with referenceto the accompanying drawings.

The present invention will be described on the basis of a universalmobile telecommunication system (UMTS) and an evolved packet core (EPC).However, the present invention is not limited to such communicationsystems, and it may be also applicable to all kinds of communicationsystems and methods to which the technical spirit of the presentinvention is applied.

It should be noted that technological terms used herein are merely usedto describe a specific embodiment, but not to limit the presentinvention. Also, unless particularly defined otherwise, technologicalterms used herein should be construed as a meaning that is generallyunderstood by those having ordinary skill in the art to which theinvention pertains, and should not be construed too broadly or toonarrowly. Furthermore, if technological terms used herein are wrongterms unable to correctly express the spirit of the invention, then theyshould be replaced by technological terms that are properly understoodby those skilled in the art. In addition, general terms used in thisinvention should be construed based on the definition of dictionary, orthe context, and should not be construed too broadly or too narrowly.

Incidentally, unless clearly used otherwise, expressions in the singularnumber include a plural meaning. In this application, the terms“comprising” and “including” should not be construed to necessarilyinclude all of the elements or steps disclosed herein, and should beconstrued not to include some of the elements or steps thereof, orshould be construed to further include additional elements or steps.

The terms used herein including an ordinal number such as first, second,etc. can be used to describe various elements, but the elements shouldnot be limited by those terms. The terms are used merely to distinguishan element from the other element. For example, a first element may benamed to a second element, and similarly, a second element may be namedto a first element.

In case where an element is “connected” or “linked” to the otherelement, it may be directly connected or linked to the other element,but another element may be existed therebetween. On the contrary, incase where an element is “directly connected” or “directly linked” toanother element, it should be understood that any other element is notexisted therebetween.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings, and thesame or similar elements are designated with the same numeral referencesregardless of the numerals in the drawings and their redundantdescription will be omitted. In describing the present invention,moreover, the detailed description will be omitted when a specificdescription for publicly known technologies to which the inventionpertains is judged to obscure the gist of the present invention. Also,it should be noted that the accompanying drawings are merely illustratedto easily explain the spirit of the invention, and therefore, theyshould not be construed to limit the spirit of the invention by theaccompanying drawings. The spirit of the invention should be construedas being extended even to all changes, equivalents, and substitutesother than the accompanying drawings.

There is an exemplary UE (User Equipment) in accompanying drawings,however the UE may be referred to as terms such as a terminal, an ME(Mobile Equipment), etc. And, the UE may be implemented as a portabledevice such as a notebook, a mobile phone, a PDA, a smart phone, amultimedia device, etc, or as an unportable device such as a PC or avehicle-mounted device.

DEFINITION OF TERMS

Hereinafter, the terms used in this specification will be brieflydefined prior to describing with reference to the drawings.

UMTS: It is an abbreviation of Universal Mobile Telecommunication Systemand denotes the 3rd mobile communication network.

UE/MS: User Equipment/Mobile Station. It denotes a terminal device.

EPS: It is an abbreviation of Evolved Packet System, and denotes a corenetwork supporting a Long Term Evolution (LTE) network. It is a networkin the form of an evolved UMTS.

PDN (Public Data Network): An independent network in which a serverproviding services is located.

PDN connection: A connection from a terminal to a PDN. That is, anassociation (connection) between a terminal represented by an IP addressand a PDN represented by an APN.

PDN-GW (Packet Data Network Gateway): A network node in an EPS networkwhich performs the functions of UE IP address allocation, Packetscreening & filtering, charging data collection.

Serving GW (Serving Gateway): A network node in an EPS network whichperforms the functions of mobility anchor, packet routing, idle modepacket buffering, and triggering MME to page UE.

PCRF (Policy and Charging Rule Function): A node in an EPS network whichmakes a policy decision to dynamically apply different QoS and chargingpolicies for each service flow.

APN (Access Point Name): As the name of an access point managed by anetwork, it is provided to the UE. That is, a text string indicating oridentifying a PDN. It is necessary to pass through a relevant P-GW inorder to access a requested service or network (PDN). An APN denotes aname (text string) predefined within the network to find the P-GW (e.g.,internet.mnc012.mcc345.gprs).

TEID (Tunnel Endpoint Identifier): An end point ID of a tunnelconfigured between nodes within a network. It is set up for each sectionin the unit of each bearer of the UE.

NodeB: It is installed outdoors as a base station of the UMTS network,and the size of the cell coverage corresponds to a macro cell.

eNodeB: It is installed outdoors as a base station of the Evolved PacketCore (EPC) network, and the size of the cell coverage corresponds to amacro cell.

(e)NodeB: It is a term indicating both NodeB and eNodeB.

Home NodeB: It is installed indoors as a base station of the UMTSnetwork, and the size of the cell coverage corresponds to a femto cell.

Home eNodeB: It is installed indoors as a base station of the EPSnetwork, and the size of the cell coverage corresponds to a femto cell.

Home (e)NodeB: It is a term indicating both Home NodeB and Home eNodeB.

MME: It is an abbreviation of Mobility Management Entity, and performs arole of controlling each entity within EPS to provide a session andmobility for the UE.

Selected IP Traffic Offload (SIPTO): Technology for offloading trafficto a wired network such as the Internet or the like, without using anetwork (e.g., 3GPP and 3GPP2) of the mobile communication operator whenthe UE transmits specific IP traffic through Home (e)NodeB or (e)NodeB.

Session: A session is a path for transmitting data, and the unit thereofmay be PDN, bearer, IP flow, and the like. The difference between eachunit may be classified with an object network overall unit (APN or PDNunit), a unit (bearer unit) classified with QoS within the unit, and adestination IP address unit.

PDN connection: A connection from a terminal to a PDN. That is, anassociation (connection) between a terminal represented by an IP addressand a PDN represented by an APN. It denotes a connection betweenentities (terminal and PDN GW) in a core network to form a session.

UE Context: Situation information of the UE used to manage the UE in anetwork, namely, situation information configured with a UE id, mobility(current location, etc.), and an attribute of the session (QoS,priority, etc.).

OMA DM (Open Mobile Alliance Device Management): A protocol designed forthe management of mobile devices such as a cellular phone, a PDA, aportable computer, etc. which performs the functions like configuration,firmware upgrade, and error report.

OAM (Operation Administration and Maintenance): A group of networkmanagement functions that provide network fault indication, performanceinformation, and data and diagnosis functions.

NAS (Non-Access-Stratum): The highest stratum of the control planebetween a UE and an MME. It supports mobility management, sessionmanagement, and IP address maintenance between a UE and a network.

NAS configuration MO (Management Object): An MO (Management Object) usedto configure parameters related to NAS functionality for a UE.

NAS level congestion control: A congestion control function of an EPSnetwork, which contains the functions: “APN based congestion control”and “General NAS level Mobility Management.

MTC: Machine Type Communication. It occurs between machines withouthuman interference.

MTC device: A UE that performs a specific object with a communicationfunction over a core network. Example) A vending machine and a meterreading machine.

MTC server: A server on a network that manages an MTC device and sendsand receives data to and from the MTC device.

MTC Application: An actual application (remote meter reading, trackingtransport of goods, etc.) which uses an MTC device and an MTC server.

MTC Feature: Some features are required according to the functions orattributes of a network for supporting an MTC application, that is,according to the purpose of each application. Examples of which includeMTC monitoring (required for remote meter reading prepared for equipmentloss), low mobility (rare mobility for vending machines).

FIG. 7 shows a procedure of rejecting access from a MTC device in caseof network congestion or overload. FIG. 8 is an exemplary viewillustrating a protocol of the message illustrated in FIG. 7.

Prior to specifically describing each procedure with reference to FIG.7, messages illustrated in FIG. 7 will be briefly described as followswith reference to FIG. 8.

The messages transmitted or received between the MTC device 100 and the(e)NodeB 200 are based on the Radio Resource Control (RRC) protocol. Themessages transmitted or received between the (e)NodeB 200 and the MME510 SGSN (not shown) are based the S1 Application Protocol (S1-AP).

The messages transmitted or received between the MTC device 100 and theMME 510 or SGSN (not shown) are based on the Non-Access Stratum (NAS)protocol. The messages based on the NAS protocol are encapsulated in amessage based on the RRC protocol and the S1-AP message and thentransmitted.

As can be seen with reference to FIG. 7( a), a network node can reject aspecific access in order to resolve network congestion or overload. Suchan access restriction is enabled according to an APN (i.e., congestedAPN) or MTC group. Such access restriction may cause the network node totransmit a back-off time to the MTC device and provide information aboutrestricting access and session setup until the duration of the back-offtime expires.

The network node may set the back-off time by using a randomizationmethod. Also, the access start time is randomized to preventsimultaneous congestion at a specific point of time.

As can be seen with reference to FIG. 7( a), when the MTC device 100performs an attach or tracking area update (TAU) procedure through a(e)NodeB 200 in case of network congestion or overload, a node, e.g.,MME/SGSN 510, within the network rejects the attach, service request orTAU request according to a network situation such as an operator policy.

Also, the MME/SGSN 510 may transmit a back-off time when it performs therejection so that the MTC device 100 does not have to attempt accessuntil expiry of the back-off time.

At this point, the MTC device 100 does not have to perform an attach,service request or TAU procedure through a second (e)Node 220 based onthe back-off time.

Alternatively, as shown in FIG. 7( b), in case of network congestion oroverload, a node, e.g., MME/SGSN 510, within the network may transmit aback-off time to the MTC device 100 through the (e) nodeB 200 accordingto a network situation such as an operator policy.

Then, the MTC device 100 does not have to perform an attach, servicerequest or TAU procedure through the second (e)Node 220 based on theback-off time.

As described above, when network congestion occurs in a 3GPP MTCnetwork, a node (MME, Serving GW, PDN-GW, MSC, SGSN, and GGSN) of a corenetwork performs NAS level congestion control to avoid or controlsignaling congestion.

The NAS level congestion control contains the functions: “APN basedcongestion control” and “General NAS level Mobility Management.

The APN based congestion control refers to (E)MM and (E)SM signalingcongestion control related to a specific APN (APN associated with acongestion state), and contains APN based Session Management congestioncontrol and APN based Mobility Management congestion control.

On the other hand, the General NAS level Mobility Management refers toavoiding congestion or overload by a node (MME, Serving GW, PDN-GW, MSC,SGSN, GGSN)'s rejecting a Mobility Management signaling request made bythe MTC device (or UE or MS) in a situation of general networkcongestion or overload.

In general, in the case that a core network performs NAS levelcongestion control, a back-off timer (Or extended wait timer from lowerlayer) value is carried in a reject message and transmitted to the MTCdevice (or UE or MS) 100. The MTC device (or UE or MS) 100 does not sendan (E)MM/(E)SM signaling request to the network until the back-off timerexpires.

The back-off timer may be classified into a Mobility Management (MM)back-off timer for controlling (E)MM signaling (e.g., Attach, TAU/RAU,service requests, etc.) and a Session Management (SM) back-off timer forcontrolling (E)SM signaling (e.g., PDN connectivity, Bearer ResourceAllocation, Bearer Modification, PDP Context Activation, PDP ContextModification requests, etc.). The MM back-off timer operates per UE, andthe SM back-off timer operates per APN and per UE, respectively.

To sum up, the MM (Mobility Management) back-off timer is a MobilityManagement-related back-off timer used for controlling networkcongestion, which is a timer that prevents the MTC device (or UE or MS)100 from making attach, TAU/RAU, and service requests during theoperation of the timer. However, in case of emergency bearer service orMPS (Multimedia Priority Service), the MTC device (or UE or MS) 100 maymake a request even if the timer is running.

The MM back-off timer value may be provided from a network (e.g., MME,SGSN, HSS, etc.) or transmitted from lower layers (Access Stratum).Also, it may be set randomly in the range of basic values between 15 to30 minutes.

The SM (Session Management) back-off timer is a SessionManagement-related back-off timer used for controlling networkcongestion, which is a timer that prevents the MTC device (or UE or MS)100 from setting up or changing an associated APN-based session duringthe operation of the timer. However, in case of emergency bearer serviceor MPS (Multimedia Priority Service), the MTC device (or UE or MS) 100may make a request even if the timer is running.

The SM back-off timer value may be provided from a network (e.g., MME,SGSN, HSS, etc.), or set randomly within up to 72 hours if the ESM/SMreject cause value is #26 (Insufficient resources).

As described above, when an MM/SM back-off timer value is provided froma network, the network operator sets the corresponding back-off value.MM/SM back-off timer values ranging from several tens of minutes toseveral hours are set according to a network situation and policy.

Meanwhile, if the MTC device (or UE or MS) 100 is a service user withhigh priority (multimedia priority service; users having access classes11-15 and accessing a network), or already has emergency bearer servicesor wants to initiate them, the relevant service request may be made evenif the MM/SM back-off timer is already running.

Generally, most MTC devices (or UE or MS) 100 are configured with a lowpriority. However, for MTC device which has to transmit data in aspecific period, it is suggested to allow the MTC device to have dualpriorities, i.e., a low priority and a normal priority (here a normalpriority is called as “a override low priority”). Such MTC device havingdual priorities can operate in a low priority and then change from beingoperated in the low priority to being operated in the normal priority(i.e., a override low priority) thereby to transmit the data.

FIG. 9 shows a procedure of barring a RRC connection in case of networkcongestion or overload.

An Extended Access Barring (EAB) was also suggested in order to handle acongestion or overload in a network. If the MTC device is configuredwith EAB, then the MTC device cannot connect to the network. That is,the EAB bars the MTC device from connecting to the network.

To configure the EAB in the MTC device 100, the MME may transmit a NASconfiguration MO including the EAB. The EAB in the NAS configuration MOhas a bit value. Bit 0 indicates the extended access barring is notapplied for the UE. Bit 1 indicates that the extended access barring isapplied for the UE.

Also, to configure the EAB in the MTC device 100, the (e)NodeB 200broadcasts system information including EAB parameters.

The following table 1 shows the EAB parameters.

TABLE 1 EAB parameters eab-BarringBitmap Extended access class barringfor AC 0-9. The first/leftmost bit is for AC 0, the second bit is for AC1, and so on eab-Category Indicates the category of UEs for which EABapplies. Value a corresponds to all UEs, value b corresponds to the UEsthat are neither in their HPLMN nor in a Public Land Mobile Network(PLMN) that is equivalent to it, and value c corresponds to the UEs thatare neither in the PLMN listed as most preferred PLMN of the countrywhere the UEs are roaming in the operator-defined PLMN selector list onthe USIM, nor in their HPLMN nor in a PLMN that is equivalent to theirHPLMN eab-Common The EAB parameters applicable for all PLMN(s).eab-PerPLMN-List The EAB parameters per PLMN, listed in the same orderas the PLMN(s) occur in plmn-IdentityList.

After receiving the EAB and the EAB parameters, the MTC devicedetermines whether the EAB is applied to itself based on the receivedthem.

If the EAB is applied, the MTC device cannot establish the RRCconnection with the (e)NodeB 200

In general, if the MTC device may be configured with a low priority, theMTC device may also be configured with the EAB. But, even if both thelow priority and the EAB are configured to the MTC device, whether toactually apply the EAB to the MTC device may depend on subscribe data oroperator's policies.

However, if the MTC device is still applied with the EAB even after theMTC device has changed from being operated in the low priority to beingoperated in the normal priority to transmit data, the MTC device cannotconnect to the network.

Therefore, similarly to the concept of the override low priority, anoverride EAB was also suggested. The override EAB can be signaled by theNAS configuration MO to the MTC device. If the MTC device is configuredwith the override EAB and if the MTC device has a data to betransmitted, then the MTC device can override (or, ignore) the EAB andtransmit the data.

As explained above, if the MTC device is configured with the dualpriorities, the MTC device can change from/to being operated in the lowpriority to/from being operated in the normal priority (i.e., theoverride low priority). However, once the MTC device is configured withthe override EAB, the MTC device always override (or, ignore) the EABand then transmit the data at any time. This attenuates the originalpurpose for introducing the EAB. Thus, the congestion or overload in thenetwork may be remained in an unsolved matter.

Accordingly, the disclosure of the present application provides someembodiments to solve the problem. In particular, the disclosure of thepresent application suggests ways to how to efficiently apply theoverride EAB to the MTC device.

FIG. 10 shows one example method according to a first embodiment.

The MTC device 100 shown in FIG. 10 may support dual priorities andoperated in an override low priority.

The MTC device then changes from being operated in the override lowpriority to being operated in the low priority according to a behaviorof an application or a request from a network. The behavior of theapplication may mean a termination of data transmission for the overridepriority.

The NAS layer of the MTC device 100 can cognize that the priority hasbeen changed (S1010). And if the NAS layer of the MTC device 100 alsocognizes that an Attach request, a TAU request or a service request isbeing prepared to be transmitted, then the NAS layer of the MTC device100 inform the lower layer, i.e., the RRC layer that it is required toapply the EAB (S1020). Alternatively, as soon as the NAS layer cognizesthat the priority is changed, the NAS layer immediately informs thelower layer, i.e., the RRC layer that it is required to apply the EAB.

The lower layer, i.e., the RRC layer applies the EAB thereby to handlethe request such as the Attach request, the TAU request or the servicerequest (S1030).

So far, it has been explained above that the MTC device 100 supports thedual priorities. Otherwise, the MTC devices 100 may support multipriorities. And, it is noted that the method shown in FIG. 10 may beapplicable to the MTC device which supports multi priorities.

Meanwhile, the first embodiment may be varied. For example, if the MTCdevice 100 is configured with the EAB, the NAS layer of the MTC device100 or an EPS Mobility Management (EMM) indicates to the lower layer,i.e., the RRC layer of the MTC device 100 for the purpose of accesscontrol that EAB applies for each request except for the following fourcases:

A first case is when the MTC device (or UE) 100 is accessing the networkwith one of the access classes 11-15.

A second case is when the MTC device (or UE) 100 is answering to paging;

A third case is when the RRC Establishment cause is set to “Emergencycall”; or

A fourth case is when the MTC device (or UE) 100 is configured to allowoverriding EAB and receives an indication from the upper layers, e.g.application layer to override EAB.

On the other hand, if the MTC device (or UE) 100 is not configured withthe EAB and if it is required to establish a NAS-signaling connection,the MTC device (or UE) 100 selects an RRC establishment cause from atable 2 below. The NAS layer of the MTC device 100 or the EMM alsoindicates to the lower layer for the purpose of access control, the calltype associated with the RRC establishment cause as specified in table2.

TABLE 2 NAS procedure RRC establishment cause Call type Attach If anATTACH REQUEST has EPS attach type not set to “originating “EPSemergency attach”, the RRC establishment cause signalling” shall be setto MO signalling except when the UE initiates attach procedure toestablish emergency bearer services. If an ATTACH REQUEST contains theDevice properties “originating IE with low priority indicator set to “UEis configured to signalling” NAS signalling low priority”, the RRCestablishment cause shall be set to Delay tolerant. If an ATTACH REQUESThas EPS attach type set to “emergency calls” “EPS emergency attach” orif the ATTACH REQUEST has EPS attach type not set to “EPS emergencyattach” but the UE initiates the attach procedure on receiving requestfrom upper layer to establish emergency bearer services, the RRCestablishment cause shall be set to Emergency call. Tracking Area If theUE does not have a PDN connection established “originating Update foremergency bearer services and is not initiating a PDN signalling”CONNECTIVITY REQUEST that has request type set to “emergency, the RRCestablishment cause shall be set to MO signalling. If a TRACKING AREAUPDATE REQUEST contains the “originating Device properties IE with lowpriority indicator set to “UE signalling” is configured to NASsignalling low priority”, the RRC establishment cause shall be set toDelay tolerant. If the UE has a PDN connection established for“emergency calls” emergency bearer services or is initiating a PDNCONNECTIVITY REQUEST that has request type set to “emergency”, the RRCestablishment cause shall be set to Emergency call. Detach MO signalling“originating signalling” Service Request If a SERVICE REQUEST is torequest user plane radio “originating calls” resources, the RRCestablishment cause shall be set to MO data. If a SERVICE REQUEST is torequest user plane radio “emergency calls” resources for emergencybearer services, the RRC establishment cause shall be set to Emergencycall. If a SERVICE REQUEST is to request resources for UL “originatingcalls” signalling, the RRC establishment cause shall be set to MO data.If a SERVICE REQUEST is triggered by a PDN “emergency calls”CONNECTIVITY REQUEST that has request type set to “emergency”, the RRCestablishment cause shall be set to Emergency call. If a SERVICE REQUESTis a response to paging where “terminating calls” the CN domainindicator is set to “PS”, the RRC establishment cause shall be set to MTaccess. If an EXTENDED SERVICE REQUEST has service type “emergencycalls” set to “packet services via S1” and is to request user planeradio resources for emergency bearer services, the RRC establishmentcause shall be set to Emergency call. If an EXTENDED SERVICE REQUEST hasservice type “emergency calls” set to “packet services via S1” and istriggered by a PDN CONNECTIVITY REQUEST that has request type set to“emergency”, the RRC establishment cause shall be set to Emergency call.If an EXTENDED SERVICE REQUEST has service type “terminating calls” setto “packet services via S1” and is a response to paging where the CNdomain indicator is set to “PS”, the RRC establishment cause shall beset to MT access. If an EXTENDED SERVICE REQUEST has service type“originating calls” set to “mobile originating CS fallback or 1xCSfallback” and is to request mobile originating 1xCS fallback, the RRCestablishment cause shall be set to MO data. If an EXTENDED SERVICEREQUEST has service type “mobile originating set to “mobile originatingCS fallback or 1xCS fallback” CS fallback” and is to request mobileoriginating CS fallback, the RRC establishment cause shall be set to MOdata. If an EXTENDED SERVICE REQUEST is a response to “terminatingcalls” paging for CS fallback, service type set to “mobile terminatingCS fallback or 1xCS fallback”, the RRC establishment cause shall be setto MT access If an EXTENDED SERVICE REQUEST has service type “emergencycalls” set to “mobile originating CS fallback emergency call or 1xCSfallback emergency call”, the RRC establishment cause shall be set toEmergency call. If an EXTENDED SERVICE REQUEST contains the “originatingcalls” Device properties IE with low priority indicator set to “UE isconfigured to NAS signalling low priority”, the RRC establishment causeshall be set to Delay tolerant.

FIG. 11 shows one example method according to a second embodiment.

The MTC device 100 shown in FIG. 11 may support dual priorities andoperated in an override low priority.

The MTC device then changes from being operated in the override lowpriority to being operated in the low priority according to a behaviorof an application or a request from a network. The behavior of theapplication may mean a termination of data transmission for the overridepriority.

The NAS layer of the MTC device 100 can cognize that the priority hasbeen changed (S1110). And the NAS layer of the MTC device 100 notifies aNAS layer of the MME 300 that the priority has been changed (S1120). Thenotification may be achieved by transmitting an Attach request, a TAUrequest or a service request to the MME 300.

The NAS layer of the MME 300 then instructs the MTC device 100 to applythe EAB in response to the change of the priority or to withdraw anappliance of the override EAB (S1130). The instruction may be deliveredby transmitting a reject message in response to the Attach request, theTAU request or the service request, or by transmitting a dedicatedmessage.

Then, the NAS layer of the MTC device 100 informs the lower layer, i.e.,the RRC layer that it is required to apply the EAB (S1140).

The lower layer, i.e., the RRC layer applies the EAB thereby to handlethe request such as the Attach request, the TAU request or the servicerequest (S1150).

So far, it has been explained above that the MTC device 100 supports thedual priorities. Otherwise, the MTC devices 100 may support multipriorities. And, it is noted that the method shown in FIG. 11 may beapplicable to the MTC device which supports multi priorities.

Meanwhile, the first and second embodiments may be varied.

For example, if the MTC device 100 is configured with the EAB, the MTCdevice 100 always applies the EAB to itself regardless of which prioritythe MTC device is operated in. Alternatively, if the MTC device 100 isconfigured with the override EAB, the MTC device 100 always override (orignore) the EAB regardless of which priority the MTC device is operatedin. Also, although the MTC device 100 is configured with the EAB or theoverride EAB, each application of the MTC device 100 may decides whetherto apply the EAB regardless of which priority the MTC device is operatedin. For this decision, the application may consider the operator'spolicy and etc.

FIG. 12 shows one example method according to a third embodiment.

As shown in FIG. 12, if the MTC device 100 tries to perform a TAUprocedure, the new MME 510 a decides whether to apply the EAB to the MTCdevice 100. On decision, the new MME 510 a may consider a subscriptiondata and/or an operator's policy/preference. The operator'spolicy/preference may be obtained from a PCRF 550 at step 9a. And, thesubscription data may be obtained from a HSS 540 at step 17.

In more detail, the TAU procedure will be explained with reference toFIG. 12.

1˜3) The MTC device 100 decides to start the TAU procedure, and thentransmit a TAU request message to (e)NodeB 300. The (e)NodeB 300delivers the TAU request message to the new MME 510 a.

4˜5) The new MME 510 a transmits a Context Request message to a old MME510 b. The old MME 510 b transmits a Context Response message includinginformation related to the MTC device to the new MME 510 a.

6) A procedure for authentication or security is performed between theMTC device 100 and the HSS 540.

7) The new MME 510 a transmits a Context Acknowledge message in responseto the reception of the Context Response message.

8) Meanwhile, the new MME 510 a transmits a Create Session Requestmessage to a new Serving Gateway (S-GW) 520 a.

9) The new S-GW 520 a transmits a Modify Bearer Request message to PDNgateway (PDN GW) 530.

9a) The PDN GW 530 executes a session modification procedure, forexample, a PCEF-initiated IP-CAN Session Modification procedure, withthe PCRF 550. The PCRF 550 is a node in an EPS network which makes apolicy decision to dynamically apply different QoS and charging policiesfor each service flow, and handles a charging process according to theSession Termination Procedure.

At this point, the P-GW 530 acquires policy information from the PCRF540. Specifically, the PDN GW 530 obtains operator policy/preferencethrough the PCRF. It is noted that the operator's policy/preferenceincludes information on applicability of the EAB according to dualpriorities or multi priorities.

10˜11) Then, the PDN GW 530 transmits a Modify Bearer Response messageincluding the operator's policy/preference to the new S-GW 520 a toserve the MTC device 100, and the new S-GW 520 a transmits a CreateSession Response including the operator's policy/preference to the newMME 510 a to serve the MTC device 100.

12˜14) The new MME 510 a transmits a Update Location message to the HSS540. Then, the HSS 540 transmits a Cancel location message to the oldMME 510 b and the old MME 510 b transmits a Cancel Location Acknowledgemessage to the HSS 540.

15˜16) The old MME 510 b may selectively transmit a lu Release commandfor instructing a RNC to lease a lu interface and receive a lu

Release Complete message from the RNC.

17) Meanwhile, the HSS 540 transmits a Update Location Acknowledgemessage including a subscription data related to the MTC device 100 tothe New MME 510 a. It is noted that the subscription data may includeinformation on applicability of the EAB according to dual priorities ormulti priorities.

18˜19) The old MME 510 b transmits a Delete Session Request message tothe old S-GW 520 b and the old S-GW 520 b transmits a Delete SessionResponse message to the old MME 510 b.

20˜21) The new MME 510 a decides whether to apply the EAB to the MTCdevice 100 based on at least one of the acquired subscription data andthe acquired operator's policy/preference which may include informationon applicability of the EAB according to dual priorities or multipriorities.

So far, it has been explained that when the new MME 510 a decideswhether to accept or reject the TAU request from the MTC device 100, thenew MME 510 a may consider a subscription data and/or an operator'spolicy/preference to decide whether to apply the EAB to the MTC device100. This concept may also be applicable when the new MME 510 decideswhether to accept or reject an Attach request from the MTC device 100.

FIG. 13 is a block diagram of the MTC device (or UE) and MME accordingto the present invention.

As shown in FIG. 13, the MTC device (or UE) 100 includes storage means101, a controller 102, and a transmission/reception unit (or a radiofrequency (RF) unit) 103. The MME 510 includes storage means 511, acontroller 512, and a transmission/reception unit (or a RF unit) 513.

The storage means 101 and 511 stores the methods illustrated in FIGS. 7through 12.

The controllers 102 and 512 control the storage means 101 and 511 andthe transmission/reception units 103 and 513. Specifically, thecontrollers 102 and 512 execute the methods stored in the storage means101 and 511, respectively. The controllers 102 and 512 transmit theabove-mentioned signals through the transmission/reception units 103 and513.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

The invention claimed is:
 1. A method for applying an extended accessbarring (EAB), the method performed by a machine type communication(MTC) device, the method comprising: receiving, by the MTC device set tooverride a low priority, a non-access stratum (NAS) configurationManagement Object (MO) including EAB information; and determiningwhether to apply the EAB based on the EAB information and a settingrelated to the low priority, to handle at least one of an attachrequest, a tracking area update request, and a service request; if theEAB is applied, except for satisfying a plurality of conditions,including a first condition specifying if the MTC device is configuredto allow overriding EAB, a second condition specifying if the MTC deviceis set to override the low priority, and a third condition specifying ifthe MTC device receives an indication from an upper layer to overrideEAB, then indicating to a lower layer that the EAB applies for at leastone of the attach request, the tracking area update request, and theservice request, wherein it is determined that the EAB is applied if thesetting is changed to the low priority from overriding the low priority,and wherein, if the EAB is applied, a radio resource control (RRC)connection is barred.
 2. The method of claim 1, further comprising:receiving system information including at least one EAB parameter,wherein the system information is broadcasted within a cell, and whereinthe at least one EAB parameter is taken into account when determiningwhether to apply the EAB.
 3. The method of claim 2, wherein the EABparameter includes at least one of: a bitmap parameter indicatingclasses for which access is barred; a category parameter indicating acategory of devices for which the EAB applies; and a list of Public LandMobile Network (PLMN).
 4. The method of claim 1, further comprising:notifying a NAS layer of a network node that the priority has beenchanged; and receiving an instruction to apply the EAB from the NASlayer of the network node.
 5. The method of claim 1, wherein: the upperlayer corresponds to a NAS layer; and the lower layer corresponds to aRRC layer.
 6. A machine type communication (MTC) device for applying anextended access barring (EAB), the MTC device comprising: a radiofrequency (RF) unit configured to receive a non-access stratum (NAS)configuration Management Object (MO) including the EAB information; aprocessor configured to: override a low priority; determine whether toapply the EAB based on the EAB information and a setting related to thelow priority, to handle at least one of an attach request, a trackingarea update request, and a service request; and if the EAB is applied,except for satisfying a plurality of conditions, including a firstcondition specifying if the MTC device is configured to allow overridingEAB, a second condition specifying if the MTC device is set to overridethe low priority, and a third condition specifying if the MTC devicereceives an indication from an upper layer to override EAB, thenindicate to a lower layer that the EAB applies for at least one of theattach request, the tracking area update request, and the servicerequest, wherein it is determined that the EAB is applied if the settingis changed to the low priority from overriding the low priority, andwherein, if the EAB is applied, a radio resource control (RRC)connection is barred.
 7. The MTC device of claim 6, wherein: the RF unitis further configured to receive system information including at leastone EAB parameter; and the system information is broadcasted within acell.
 8. The method of claim 7, wherein the EAB parameter includes atleast one of: a bitmap parameter indicating classes for which access isbarred; a category parameter indicating a category of devices for whichthe EAB applies; and a list of Public Land Mobile Network (PLMN).
 9. Themethod of claim 6, wherein the processor is further configured to:notify a NAS layer of a network node that the priority has been changed;and receive an instruction to apply the EAB from the NAS layer of thenetwork node.
 10. The method of claim 6, wherein: the upper layercorresponds to a NAS layer; and the lower layer corresponds to a RRClayer.